Circuit interrupting device



Sept. 5, 1939. s. T. SCHOFIELD ET AL 2,172,225

CIRCUIT I'NTERRUPTING DEVICE Filed Feb. 20, 1937 3 Sheets-Sheet l G xmS INVENTORS Stanley 7750/20 z'eld Deceased 13y Mart/7a MScho/iel ,Admimszr'azrix and Jag es Mi Takes. v 'TTOR Y Sept-5, 1939. s. T. SCHOFIELD ET AL 2,172,225

I CIRCUIT INTERRUPTING DEVICE 3 SheetsSheet 2 Filed Feb. 20, 1937 INVENTORS leialflecease 5 H. F'rake ATTO E Sept. 5, 1939. s. T. SCHOFIELD ET AL 2,172,225

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, at least during Patented Sept. 5, 1939 2,172,225 CIRCUIT INTERRUPTING DEVICE Stanley '1. Schofield, deceased, late oi Wilkinsburg, Pa., by Martha M. Scholield, administratrix, W

ilkinsburg, Pa., and James H. Frakes, Wilkinsburg, Pa., assignors Electric & Manufacturing to Westinghouse Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 20, 1937, Serial No. 126,890

12 Claims.

This invention relates to circuit interrupting devices and more particularly to load break disconnect switches. In the transmission of electrical energy over lines having moderate voltage and power requirements, the revenue which may be derived therefrom does not always warrent the cost of installing the customary switching equipment, such as disconnect switches and circuit breakers. It has been found that by providing a circuit interrupter which functions as a disconnect device and also as a load current interrupter, separate disconnect switches and circuit breakers may be eliminated thereby effecting a considerable saving in the cost of switching equipment.

Overload protection in conjunction with a cir-- cuitinterrupter of the type to be hereinafter fully described may be obtained by the use of fuse devices whichare relatively inexpensive to manufacture.

The main object of the invention is to provide a circuit interrupter capable of disconnecting the connected circuit under conditions of load from its source of supply.

Another object of the invention is to provide a load break disconnect switch in which the open- V ing movement of the switch is utilized to actuate the contacts of an arc extinguishing structure for effecting load current interruption subsequent to the separation of theswitch contacts.

A further and more specific object of the invention is to provide a load break disconnect switch in which the switch blade is connected its opening movement with an arc extinguishing structure for causing current normally flowing through the switch to be transferred to the arc extinguishing circuit and in which the are extinguishing contacts are actuated to the open circuit position by the further opening movement of the switch blade.

An ancillary object of the invention is to provide a load break disconnect switch of the type above described in which the final break during the opening operation takes place between the movable contact of the arc extinguishing device and a member carried by the switch blade, which member is adapted to be disengaged from the contact with a snap action.

Other objects and advantages relate to details of the switch structure and will appear more fully in the following description taken in connection with the accompanying drawings, in which Figure 1 is a side elevational view of the switchend portion of one of ing device of the invention showing the circuit interrupting portion partially in section.

Fig. 2 is a sectional view of the device shownv in Fig. 1, taken along the line IIII of that figure.

Fig. 3 is an enlarged side view showing the the switch blades and the actuating member in its attached interrupter normal position.

Fig. 4 is a sectional view taken along the line IV-1V of Fig. 5, showing the interrupter actuating member in a stressed position.

Fig. 5 is a plan view of the fragmentary switch blade portion shown in Fig. 4.

Fig. 6 is a vertical sectional view of the circuit 15 interrupter portion of the switching device.

Fig. 7 is a cross sectional view taken along line VII-VII of the circuit interrupter shown in Fig. 6.

Fig. 8 is a cross line VIII- VHI of in Fig. 6, and a Fig. 9 is a cross sectional view taken along the line IXIX of the circuit interrupter shown in Fig. 6. 25

Referring to the drawings, the reference numeral l0 designates a base upon which are mounted insulators Ii, i3 and I5. Each of the insulators has a metallic cap portion ll secured to the upper end thereof. A metallic terminal 30 plate i8 interconnects the cap portion ll of insulators l3 and IS. The insulator I3 is provided with a U-shaped bracket i9 to which is pivoted a forked member 2i by means of bolt 23. The

sectional view taken along the 20 the circuit interrupter shown forked member 2| carries a blade member 25, the 35 free end of which is provided with a serrated contact portion 21 adapted to engage the toothed portion 29 of the U-shaped contact member 3| mounted upon the cap I! of the insulator i I.

The bolt 23 pivotally supports one end of a pair of links 33, whereas the other ends of the links 33 are pivotally connected by means of a bolt 35 to a forked member 31 which, in turn, supports one end of a second blade member 39. The other end of the blade member 39 is provided 5 with a contact portion ll adapted to engage the side portion 43 of the contact member 3|. The two contact portions 21 and II are coupled to each other by means of a pair of links 45. Due to the pivotal linkages 33 and 45, the blade mem- 1 her 39 is permitted to move longitudinally with respect to the blade 25.

It will be observed that as the blade 39 is moved to the right (Fig. 1), the coupling linkage 45 allows the contact portions 21 and II of the blade members 25 and 39, respectively, to move toward each other, thereby releasing the high pressure engagement of these contact members with the fixed contact 3|, which, in turn, permits the entire blade assemblage to be swung upwardly about the pivotal pin 23 to an open position. During the closing operation of the switch blade assemblage, the blade member 39 is adapted to be moved. to the left and in so doing is actuated by the linkage 45 to cause the contact portions 21 and 4| to make a high pressure engagement with their respective cooperating contact portions 29 and 43 of the contact member 3|. The cooperating contact portions 4| and 43 are smooth so as to provide for a high pressure wiping engagement, Whereas the contact portions 21 and 29 are toothed for the purpose of positively interlocking the insulator columns II and I3 when the switch is in the closed circuit position.

The switch assemblage is actuated to open and closed position by means of the insulator I5 which is provided with a shaft 41 journalled in a suitable bearing 49 mounted on the base I0. The upper portion of the rotatable insulator I5 is provided with an offset crank head 5| provided in this instance with crank pin bearings 53 and 55, respectively. The forked member 2| is provided with a short upstanding arm 5'! which is coupled through a universal joint 58 toone end of an actuating rod 59, the other end of. which is coupled by means of a universal joint 6| to the crank pin bearing 55. To the pivotal pin 35 is joined by means of a universal coupling 63 an actuating rod 65, the other end of which connects with the crank pin bearing 53 through a universal coupling 61'.

The crank pin bearing 55, as more clearly shown in Fig. 2, is slightly ofiset with respect to the center line joining the insulator'columns I3 and I5 and has a lesser throw than the crank pin bearing 53, which is in alignment with the line joining the centers of the insulator columns I3 and I5 when the switch is in the normal or closed position. In opening the switch, the in sulator column I5 is rotated counter-clockwise as viewed in Fig. 2. It will be noted that during the initial rotative movement of theinsulator I5, the crank pin bearing 53 in crank head 5| will cause the supporting links 33 to be rocked about the pivotal pin 23 causing longitudinal movement of the switch blade 39 so as to release the high pressure engagement between the contact portions 21 and 4| and their cooperating contact members 29-and 43. Since crank pin bearing 55 is positioned past dead center and has a lesser throw than the crank pin bearing 53, the former is permitted to travel through a considerable arc before imparting movement to the actuating rod 59, which subsequently moves to the right as viewed in Fig. 1 and rocks the entire blade assemblage about the pivotal pin 23 to the open circuit position. It is thus seen that the relative positions of the crank pin bearings 53 and 55 produce, in effect, a time delay during the opening movement of the switch blade assemblage, which is sufficient to enable the high pressure contact to be broken prior to the actual movement of the blade assemblage to the open position.

In closing the switch blade assemblage, the reverse operations take place. It will be noted that the particular actuating linkage including the two operating rods 59 and 65 and their respective couplings to the crank head 5| maintain the blade members 25 and 39 in the collapsed position at all times during which the contact portions 21 and GI are not in high pressure engagement with the fixed contact 3|.

The contact 3| is provided with a terminal member I which carries conducting plate II bolted thereto or secured in any other suitable manner. The plate II serves as a support for an arc extinguishing device generally indicated at 13. The are extinguishing device I3 comprises a cylindrical base I preferably of magnetic material, a metallic head portion 11 and an intermediate casing I9 of porcelain or other insulating material, which portions are adapted to be held in assembled relation with respect to each other by means of an insulating tie bolt 8|, the upper end of which has threaded engagement with the head 11 and the lower portion of which extends through the conducting support plate TI and is provided with a nut 83.

The base portion I5 and porcelain section I9 are lined with a cylindrical member 85 of insulating material. Within the lower portion of the cylindrical liner 85 is positioned a coil 81, one terminal of which is connected to the conducting support plate II, and the other terminal of which is connected to an annular contact plate 89. Within the coil 81 is disposed a tubular lcore 88 of magnetic material which extends upwardly slightly beyond the upper edge of the base 15. Immediately above the annular contact plate 89 is a cylindrical member 9| preferably of fiber or other suitable insulating material, which serves as the outer wall of an endless arc passage 93. The cylindrical member 9| also serves as a spacing member for supporting an upper annular arcing plate 95 which is maintained in rigid engagement with the spacing member 9| by means of an annular insulating member 91.

The inner wall of the tubular arc passage 93 comprises atubular lower section 99 of fiber or other insulating material and a tubular upper section consisting of aplurality of annular membars I0| preferably of compressed boric acid or centric relation about the tie bolt 8| and held in compression between the lower annular contact member 89 and the upper annular arcing contact 95.

The arc passage 93 has an enlarged portion I03 as more clearly shown in Figs. 8 and 9 for the purpose of accommodating a movable contact member I05. Contact member I05 extends upwardly through a suitable aperture in the annular spacing member 91 and is provided with a series of insulating guide tubes I01, I08 and I09, which, in addition to giving the contact member lateral support, also insulate it from the metallic head TI. The upper portion of the movable contact member I05 is provided with a hook or projection III, the purpose of which will appear more fully hereinafter.

Immediately below the hook II I is a hood I I3 which is secured to the contact member I05 and movable therewith. The hood I I3 extends downwardly over the opening in the tube I01 so as to prevent the entrance of icev and snow or moisture into the arc chamber. A guide rod 5 is also provided having its lower end screw threaded into the head I1 and which extends upwardly through a suitable aperture in the upper wall of hood H3. The upper end of guide secured to arm I3I and the porcelain casing 19.

rod II5 may be provided with nuts II1 which serve as stops to limit the upward movement of the movable contact member I 05. The contact member I 05 is biased to the circuit closing position by means of a coil tension spring II9 encircling the guide rod II 5 and having its upper end anchored to the hood H3 at I2I and its lower end anchored to the head 11 at I23. One side of the hood H3 is provided with an inclined portion I 25 which has an extension I21 extending downwardly and terminates adjacent The surface I25 is continued upwardly toward the hook III by means of a metallic filler member I29 thereby providing an elongated substantially flat contact surface, the purpose of which will be subsequently described.

To the inner face of contact member 21 of the blade 25 is secured a projecting arm I3I. Pivoted to the end of arm I3I about a bolt I 33 and sleeve I35 is a U-shaped bracket I31, which carries a curved con-tact actuating member I39, the free end of which is adapted to engage the inclined contact surfaces I25, I21 and I29. The actuating member I 39 is biased to a normal angular position with respect to the arm I3I by means of a coiled spring I encircling the sleeve I 35. The ends of the spring I4I terminate on opposite sides of the central portion of the bracket I31 and also upon opposite sides of a guide pin I43 extending in parallel relation with the sleeve I35. The position of pin H3, as particularly shown in Fig. 3, determines the normal position of the actuating member I39 with respect to the arm I.3I and the switch blade 25. It should also be observed that as the actuating member I39 is rotated either clockwise or counter-clockwise, as viewed in Fig. 3, such rotation will be against the bias of the spring MI. In the position shown in Fig. 1, the actuating member I39 is biased into contacting engagement with the contact surface I21 of the movable contact I05.

During the opening operation of the switch blade 25, actuating member I39 is maintained in contacting engagement with the surfaces I21, I25 and I29. As the upper end of actuating member I 39 strikes the hook III, further rta-' tive movement of the switch blade 25 causes the movable contact member I05 to be moved to its full open position against the bias of spring II9. Upon further rotative movement of the switch blade 25 to the open circuit position, the actuating member I39 is rotated about its pivot at I 33 against the bias of spring I4I. In the dotted position shown at I45 in Fig. 1, the actuating member I39 is ready to disengage from the hook III. Further rotative movement of the blade 25 will affect the disengagement, allowing the member I 39 to be moved to its normal position as shown by the dotted lines at I41 in Fig, 1, which is substantially the full open position of the switch blade 25. Upon the release of the member I39 from the hook III, contact I05 is quickly moved to the closed position by the action of spring II9. Thus, the contact portions of contact member and hook III separate under the biasing action of springs II 9 and I 4| which causes disengagement to take place with a. snap action.

During the closing operation, actuating member I39 being biased to its normal position will strike the free end of hook III and upon further movement of the blade 25 toward the closed position will cause the member I39 to strike the moving contact I05. This arc must exist in the narrow cylindrical passage surface I25 with a hammer-like action, thus insuring a good contact between the member I39 and the surface I25 even though the latter be coated with sleet or ice. Likewise, the hammerlike action of the actuating member I 39 during its upward movement in striking the hook I II will insure a good contact between the member and the contact I05 during the opening movement of the switch.

The electrical circuit through the switch when it is in its normal or closed position is from the terminal I8, bracket I9, blades 25 and 39, contact 3|, and terminal 10. A circuit also exists between the contact portion 21, arm I 3|, actuating member I39, contact surface I21, I25, contact I05, contact 89, coil 81, support plate H and terminal 10. However, since this latter circuit has a considerably higher resistance than that of the contact member 3|, only a very small portion of the load current will flow through the interrupter circuit 13 when the switch blades 25 and 39 are in the closed circuit position. But, during the opening movement of the switch blades 25 and 39 after the latter have cleared the fixed contact 3I, the current flow is from the terminal I8, bracket I9, switch blades 25 and 39, arm I 3I, actuating member I39, contact surface I25, movable contact I05, fixed contact 89, coil 81, support plate H and the other line terminal 10.

Upon the separation of contacts I05 and 89 by the upward movement of actuating member I39, an arc is drawn within the chamber 93. Current flowing through the coil 81 produces a radial magnetic field across the tubular arc passage 93 which forces the are from the enlarged portion I03 of the passage into the constricted portion, thus causing the arc to intimately contact the walls thereof. The base 15 and the core 88 provide for the uniform distribution flux across the arc passage 93. The action of the arc against the walls constituted by the fiber members 9I and 99 aswell as the boric acid lining members IOI, produces considerable quantities of arc extinguishing gas which are effective in aiding'the extinction of the arc. As the arc is rotated in the slot-like passage 93, the ends thereof form terminals upon the fixed con-tact 89 and the upper annular arcing contact 95. The moving contact I05 moves upwardly beyond the upper contact plate 95, as indicated by the dotted position shown in Fig. 1, thus causing a second section of the arc to be formed between the arcing plate 95 and the lower end of the second section of the provided by the insulating tube I01. Inasmuch as the tube I01 provides the only means for venting the gaseous products of the are from within the chamber 93, the are within the tube I01 is thereby subjected to a longitudinal blast of arc extinguishing gas of considerable velocity. Thus, arc extinction is particularly effective due to the double action of the arc extinguishing gas upon two independent sections of the arc.

The are extinguishing structure herein described is simple in construction, and due to its efficient arc extinguishing action may be 50 restricted in mass and external dimensions as to permit mounting thereof on the line terminal connection of a large variety of disconnect switches now in service. The simple but eflicient actuating means employed for opening the circuit interrupter contacts render the problem of converting an existing switch into a load break disconnect device less diflicult.

of magnetic Although a particular load break disconnect switch combination has been shown and described, it is to be understood that the same is for the purpose of illustration and that changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the appended claims.

It is claimed:

1. In a circuit interrupter, a pair of spaced conducting members, movable blade means for bridging said conducting members to establish an electrical circuittherebetween, means for moving said blade means into and out of engagement with at least one of said conducting members, an arc extinguishing device having separable contacts, one of which is connected to the said one of said conducting members, said separable contacts being in closed position when said blade means moves out of engagement with said one of said conducting members and means for releasably connecting said blade means in circuit with the other of said separable contacts to establish a second circuit between said conducting members and in parallel with the gap formed between said blade means and said one conducting member, said connecting means including means for actuating said separable contacts to open position to establish an arc therebetween following the disengagement of said blade means from the said one of said conducting members.

2. In a circuit interrupter, a pair of spaced conducting members, movable blade means for bridging said conducting members to establish an electrical circuit therebetween, means for moving said blade means into and out of engagement with at least one of said conducting members, an arc extinguishing device having a pair of separable contacts, one of which is connected to the said one of said conducting members, and means for releasably connecting said blade means with the other of said separable contacts to establish a second circuit between said conducting members, said connecting means being movable with said blade means and including means permitting said separable contacts to remain in engagement during the disengagement of said blade means from said one of said conducting members and movable to cause actuation of said separable contacts to open position and finally disconnecting from said other separable ,contact upon further movement of said blade means.

3. In a circuit interrupter, a pair of spaced conducting members, a movable blade member for bridging said conducting members to establish an electrical circuit therebetween, means for moving said blade member intoand out of engagement with at least one of said conducting members, an arc extinguishing device having a pair of separable contacts, one of which is connected to the said one of said conducting members, and a connecting member pivotally mounted on the end of said blade member, said connecting member having limited sliding engagement with said other separable contact during the disengagement of said blade member from the said one of said conducting members and positive engagement with said separable contact following the disengagement of said blade member from the said one of said conducting members to cause a predetermined separation of said separable contacts upon further movement of said blade member, said conducting member being completely disconnected from said separable contact upon final movement of said blade member to its open circuit position.

4. The combination with a switch having a contact, a blade and means for moving said blade into and out of contacting engagement with said contact of an arc extinguishing device having a fixed contact connected to said first contact, a cooperating contact member movable to open and closed positions, an actuating member pivotally mounted to one end of said blade, means biasing said actuating member into engagement with said contact member, said actuating member making sliding engagement with said contact member during the disengagement of said blade from said contact, means associated with said contact member for positively engaging said actuating member upon further movement of said blade to thereby cause separation of said fixed contact and said contact member, said contact member being disposed with respect to said actuating member to release the latter upon said .contact member reaching its full open position,

said biasing means being operative to cause the separation of said contact member and said actuating member with a snap action.

5. The combination with a switch having a contact, a blade and means for moving said blade into and out of contacting engagement with said contact of an arc extinguishing device having a fixed contact connected to said first contact, a cooperating contact member movable to open and closed positions, an actuating member pivotally mounted to one end of said blade, means biasing said actuating member into engagement with said contact member, said actuating member making sliding engagement with said contact member during the disengagement of said blade from said contact, means associated with said contact member for positively engaging said ac tuating member upon further movement of said blade to thereby cause separation of said fixed contact and said contact member, said contact member being disposed with respect to said actuating member to release the latter upon said contact member reaching its full open position, said biasing means being operative to cause the separation of said contact member and said actuating member with a snap action, and means for moving said contact member into engagement with said fixed contact upon the release of said actuating member.

6. A circuit interrupter comprising a fixed contact, a cooperating contact member movable to open and closed positions, a second fixed contact in circuit with said first contact, a blade member mounted for swinging movement into and out of engagement with said second contact,

a conducting member pivoted to one end of said blade member, means biasing said conducting member to a predetermined position with respect to said blade member, said biasing means maintaining said conducting member in contact with said contact member during the disengagement of said blade member from said second contact and means associated with said contact member for positively engaging said conducting member for moving said contact member to open circuit position in response to further movement of said blade member towards its open circuit position, said biasing means cooperating with said en-' gaging means to release said conducting member with a snap action when said contact member has reached full open position.

'7. The combination with a switch having a contact and a blade member operable into and out of engagement with said contact of an are extinguishing device having an arc chamber, a fixed contact therein permanently connected to said switch contact, a cooperating movable contact member, means carried by said blade member and operable at least during the initial movement thereof to open circuit position for connecting said contact member in circuit with said blade member, said means being operative following the disengagement of said blade member from said switch contact to positively actuate said contact member to open position to thereby establish an arc within said are chamber, said means being adapted to break the connection between said blade and contact members upon the latter member reaching its full open position, and means biasing said movable contact member towards said fixed contact for automatically returning said movable contact member to its closed position upon release of the connection between said blade and said movable contact member.

8. The combination with a switch having a contact and a blade member operable into and out of engagement with said contact of an arc extinguishing device having an arc chamber, a fixed contact therein permanently connected to said switch contact, the movable contact member having a portion normally within said arc chamber for cooperation with said fixed contact and a portion extendng externally of said are chamber, said exterior portion having an elongated contact surface and engageable means disposed adjacent said surface, means for normally biasing .said contact member into engagement with said fixed contact, the conducting member carried by said blade member being adapted to slidably engage said contact surface to establish the circuit through said are extinguishing device at least during the disengagement of said blade member from said switch contact, said connecting means being adapted to engage said engageable means following the separation of said blade member and said switch contact to actuate said contact member to the open circuit position against the action of said biasing means, said connecting means being adapted to release said contact member upon the latter member reaching its full open position as a result of further movement of said blade member to the open circuit position.

9. The combination with a switch having a contact and a blade member operable into and out of engagement with said contact of an arc extinguishing device having an arc chamber, a fixed contact therein permanently connected to said switch contact, a, cooperating movable contact member, means carried by said blade member and operable at least during the initial movement thereof to open circuit position for connecting said contact member in circuit with said blade member, said means being operative following the disengagement of said blade member from said switch contact to actuate said contact member to open position to thereby establish an are within said arc chamber, said means being adapted to break the connection between said blade and contact members upon the latter member reaching its full open position and means for returning said contact member into engagement with said fixed contact upon said blade reaching full open position.

10. The combination with a switch having a contact and a blade member operable into and out of engagement with said contact of an arc extinguishing device having an arc chamber, a fixed contact therein permanently connected to said switch contact, a cooperating movable contact member, means biasing said movable contact member into engagement with said fixed contact, means carried by said blade member and operable at least during the initial movement thereof to open circuit position for connecting said contact member in circuit with said blade member, said means carried by said blade member being operative following the disengagement of said blade member from said switching contact to actuate said contact member to open position against the action of said biasing means to thereby establish an arc within said arc chamber, said biasing means assisting said means carried by said blade member to break the connection between said blade and contact members with a snap action.

11. In a circuit interrupter, a pair of spaced conducting members, movable blade means for bridging said conducting members to establish an electrical circuit therebetween, means for moving said blade means into and out of engagement with at least one of said conducting members, an arc extinguishing device mounted on said one of said conducting members and having separable contacts, one of which is connected to the said one of said conducting members, said separable contacts being in closed position when said blade means moves out of engagement with said one 01 said conducting members, and means for releasably connecting said blade means in circuit with the other of said separable contacts to establish a second circuit between said conducting members and in parallel with the gap formed between said blade means and said one conducting member, said connecting means including means for actuating said separable contacts to open position to establish an arc therebetween following the disengagement of said blade means from the said one of said conducting members, and said blade means moving to cause release of said releasable connecting means after causing actuation of said separable contacts to open position and then moving to a distance from said are extinguishing device to establish an isolating gap capable of withstanding high voltage.

12. In a circuit interrupter, a pair of spaced conducting members, movable blade means for bringing said conducting members to establish an electrical circuit therebetween, means for moving said blade means into and out of engagement with at least one of said conducting memhere, an arc extinguishing device having therewithin a pair of arc establishing contacts, one of which is connected to the said one of said conducting members, and means for releasably connecting said blade means with the other of said are establishing contacts to establish a second circuit between said conducting members, said connecting means including a part movable with said blade means and including means permitting said are establishing contacts to remain in engagement during the disengagement of said blade means from said one of said conducting members and being movable to cause actuation of said are establishing contacts to open position and finally disconnecting from said other are establishing contact upon further movement of said blade means, and said blade means after disconnection from said other are establishing contact moving to establish a wide gap in air from said are extinguishing means.

MARTHA M. SCHOFIELD, Administratrisc of the Estate of Stanley T. Schofield, Deceased.

JAMES H. FRAKES. 

